Boy or Girl? If it is really important to you to either have boy or girl children, you need to take a look at your husband's family tree. Since women have two X chromosomes and men have XY chromosomes, it is the man who determines the sex of a child. If you husband's family has a lot of girls and not many boys, he will be more likely to father girls. Exponentially so if that same trait flows from generation to generation. Sometimes there are oddballs that are the opposite of the family tree, but there are many more that follow this statistically link.